The most common abuse of correlation in studies is to confuse the concepts of correlation with those of causation.

Examples:

No correlation: Height of a student and good grades

The height of a student has no relationship to good grades.

A correlation but not causation: Good SAT scores and good grades

Many times, you will find students with good SAT scores also making good grades, but good SAT scores do not cause good grades. Many times there are other variables, such as good study habits, that contribute to both.

Causation: Study time and good grades

The amount of time a student studies does CAUSE grades to be GOOD. Note: Causation statements are not the same as a statement in logic. For example: If you jump in a swimming pool, you will get wet. If you don't jump in the swimming pool, you will not get wet. This will occur all the time if the pool is full of water. Causation is a little different. If you study, you are not guaranteed good grades. If you don't study, you are not guaranteed bad grades. We still can say that study time is one major cause of good grades.

Assignment:

Find an example of an article that that relates two variables. Is the article stating that the two variables are correlated or that they have a causal relationship? Does the article confuse correlation and causation? Discuss other variables that could contribute to the relationship between the variables.